This is a great reminder to just let them dry on the vine/bush like that. I found mine actually had this wonderfully beautiful spots on them when I cracked some of my dried ones open. I will have to see if I can get a picture when I am home from work.
Do you have the issue of Frost where you are? I am just wondering as this is my first time trying to save seeds, and not sure how it effects the seed collection.
RE: GARDENING FOR FUN AND SEEDS -seed saving method for green beans